The present invention relates to a tail unit for a missile, such as a rocket which is to be propelled, at supersonic speed.
Rockets are generally stabilized by means of straight or curved blades fixed to the periphery of a cylindrical body which can constitute the actual missile body or a sleeve mounted thereon. The curved blades of known tail units all have their concavity turned in the same direction around the cylindrical body.
In flight a rocket is subject to a periodic pitching movement, to an imposed rotational rolling movement to compensate aerodynamic mass or propulsive asymmetries and to a disturbing yawing movement.
Curved blades have in the air an asymmetrical flow which produced a lateral force perpendicular to the plane of incidence. At low speeds this force is negligible and does not significantly disturb the flight of the rocket. At high speeds above e.g. Mach 2 this force reaches high values and produces a linking of yawing and pitching movements leading to a precession movement which causes serious disturbances to the rocket trajectory.